A US woman who shot and killed her husband and two adult children before taking her own life is thought to have committed the shocking crime as a result of being ostracised from the religion she was raised in.

Every time I tell a mate I’m doing a story on cryptocurrency, they invariably ask me the same two questions: should they invest their own hard-earned money, and which cryptocurrency will get them a Lamborghini/yacht/island quickest?

NSW's one-punch law 'knee-jerk': critics

Plans to introduce a "one punch" offence for king-hit killers in NSW have been labelled knee-jerk.

Critics argue it will do nothing to address the real problem of drink and drug-fuelled violence.

Premier Barry O'Farrell was reportedly expected to take legislation to cabinet on Monday evening, outlining an offence similar to Western Australia's unlawful assault causing death laws.

It comes days after the sentencing of Kieran Loveridge sparked mass outcry when he received a minimum of four years for killing teenager Thomas Kelly in an unprovoked attack in Sydney's Kings Cross earlier this year.

Bar Association president Phillip Boulten SC has warned against introducing legislation while temperatures are high.

"It's never a good thing to make laws on the run, especially in the wake of an emotional response to a particular case," he told AAP.

While the "one punch" provision would reportedly carry a 10-year maximum sentence, Mr Boulten pointed out that manslaughter can already see offenders sent to prison for 25 years.

"There is some chance that the pattern for sentencing will be less severe," he added.

Principal solicitor at Shopfront Youth Legal Centre Jane Sanders also called for a calm approach.

"There may well be an appeal (in the Loveridge case) and quite possibly the Court of Criminal Appeal will find that the sentence was inadequate," she told AAP.

If the government then feels legislative change is necessary they should go through a proper inquiry to draft the best possible laws, she added.

Ken Marslew, founder of anti-violence organisation Enough is Enough, said while he believed the Loveridge sentence was insufficient, the culprit was not legislation.

"We have the laws in place ... it's the administration of those laws that is the problem," he told AAP.

He accused the government of running a political campaign and said it had failed to deal with the alcohol and drug-fuelled violence at the root of the problem.

Greens MP David Shoebridge said the focus should be on preventing these assaults, "something that requires long-term planning and a commitment to evidence-based policy making rather than just more knee-jerk law-and-order announcements".

But there have been some advocates of the proposed changes.

Former NSW Director of Public Prosecutions, Nicholas Cowdery, said it would help deal with the grey area between murder and manslaughter and stop undue expectations of sentence length.

Loveridge was initially charged with murder, but this was later downgraded to manslaughter in exchange for a guilty plea.

Opposition Leader John Robertson said he was open to the changes, telling Fairfax Radio: "If our legal system doesn't meet community expectations then it's failing".

After News Corp ran the story on the proposed changes on Monday, Mr O'Farrell's office said he was not planning further media comment.

Mr Marslew said Enough is Enough would host a rally at Sydney's Hyde Park next Tuesday to protest "lenient sentences".

Thomas Kelly's mother, Kathy Kelly, said she was heartened by the public response.

She told ABC radio she hadn't seen details of what the NSW government was considering, but believed the public wanted action.

"People have just had enough. They've absolutely had enough, and they want change," she said.

Mrs Kelly said she understood tougher jail terms could cost the taxpayer, but felt it was worthwhile.

"As a citizen of this country, I would rather see that money get taken away from our education and taken away from other areas and put into putting these people away, because we are not safe on our streets," she said.